Windows are commonly accepted as the source of the greatest loss of energy in the home. That is, a great deal of heat is lost through the windows during the winter and a great deal of unwanted heat is admitted through windows during the summer. There are many ways to reduce the undesirable transfer of heat through the windows. One is to eliminate the window entirely. This is a rather unacceptable solution for it also eliminates aesthetically pleasing views through the window, desirable solar energy gains through the window during the daytime in the winter, and ventilation through the window when opened.
Another method to prevent heat transfer through windows is to use either insulated shutters mounted to the window frame or removable insulated panels. These methods also have their drawbacks. Exterior shutters are inconvenient at best. Interior shutters often cannot be used because of their bulk and can be objectionable from an aesthetic standpoint. Removable insulated panels, which are simply insulated panels made to fit within the window frame, are difficult to store when not in use and are usually less than attractive. A third method is use of reflective film which may be placed on the window to reflect the summer sun, but it also reflects desirable winter sun as well. Further, the film provides a very small degree of insulation from conduction heat loss through the window during the winter and allows a significant amount of radiant heat to enter into the room during the summer.
Another method of insulating windows is through the use of quilted window shades. Quilted shades are typically housed on a roller and can have their edges adapted to run along a track along the sides of the window. However, these shades often require somewhat complicated and bulky roller arrangements and generally are not attractive.
Conventional draperies offer some insulation to windows, are attractive, convenient to use and can be drawn to admit winter sunlight. However, presently available insulated draperies are either excessively bulky so they do not drape properly and are rather unattractive, or they are made of materials which may drape well but are relatively poor insulators.